In recent years, lightness and stiffness are required for housings of OA equipment such as laptop computers and printers, machine components, or members such as an insole of prosthetic legs. For such members, a carbon fiber-reinforced plastic has been used in which a plurality of carbon fiber prepregs obtained by impregnating carbon fibers with a resin and then semi-drying are laminated and then integrated by heating and pressing.
Conventionally, in order to obtain a carbon fiber-reinforced plastic having a convex portion or a concave portion formed on a surface thereof to have different thicknesses in accordance with regions thereof, as shown in FIG. 10, the number of carbon fiber prepregs 91A to 91G needs to be varied in accordance with each of regions of different thicknesses, and also the carbon fiber prepregs need to be laminated and integrated at exaction positions. Also, in this case, the carbon fiber prepregs 91A to 91G to be laminated have to be prepared to have a number of different shapes conforming to those of regions, on which the carbon fiber prepregs are to be laminated. Therefore, because types of carbon fiber prepregs required are drastically increased to complicate both of preparation and shaping of the carbon fiber prepregs, this technique is not practical.
Further, there is a case where a plurality of carbon fiber prepregs are laminated and then pressed and heated by a pressing mold having mold surfaces previously provided with unevenness, so that the unevenness is formed on surfaces of a carbon fiber-reinforced plastic. In this case, the plurality of carbon fiber prepregs are pressed and formed by a convex portion on one mold surface and a concave portion on the other mold surface. Therefore, as shown in FIG. 11, a carbon fiber-reinforced plastic 90 made of a plurality of carbon fiber prepregs 92A, 92B, 92C and 92D is configured so that a convex portion 95 on one side thereof and a concave portion 96 on the opposite side are formed in pairs, and as a result, there are restrictions on shapes thereof. In addition, only a carbon fiber-reinforced plastic of a constant thickness, in which a normal portion 91, which does not have unevenness, the concave portion and the convex portion are all formed at the same thickness, is obtained, and thus ones whose thickness is partially varied cannot be obtained. Therefore, a degree of freedom in design is low and there are restrictions on applications thereof.
[Patent Document 1] JP-A-2012-106461
[Patent Document 2] JP-A-2004-209717
[Patent Document 3] JP-A-H07-243147